One of the most popular methods for measuring the mass flow rate through a conduit involves the measurement of the flexural vibration of a section of the conduit providing the flow passage and determination of the mass flow rate from a component of the flexural vibration of the conduit, by which component the flexural vibration deviates from that of the conduit containing stationary media. For example, when a straight or curved conduit with two extremities fixedly secured to a rigid support having a configuration symmetric about the midsection thereof is vibrated laterally by an electromagnetic vibrator exerting a vibratory lateral force to the midsection of the conduit, the conduit displays a pattern of flexural vibration that is symmetric about the midsection thereof as long as there is no media moving through the conduit. The reaction by the moving media contained in the conduit to the flexural vibration of the conduit generates a secondary flexural vibration of the conduit, that is antisymmetric about the midsection of the conduit, as the media moving through the conduit absorbs the momentum of the flexural vibration from the vibrating conduit in the inlet half of the conduit and releases this momentum back to the conduit in the outlet half of the conduit. The intensity of the antisymmetric component of the flexural vibration of the conduit is directly proportional to the mass flow rate of the media moving through the conduit and, consequently, the mass flow rate can be determined from the intensity of the antisymmetric component of the flexural vibration of the conduit. In present day practice, a pair of motion detectors respectively measuring the velocities of the flexural vibrations of the two halves of the conduit provide information on the phase angle difference between the flexural vibrations of the two halves of the conduit and the mass flow rate is determined from the phase angle difference, as the amplitude of the antisymmtric component of the flexural vibration of the conduit is directly proportional to the phase angle difference as long as the amplitude of the flexural vibration remains small. The secondary flexural vibration or the antisymmetric component of the flexural vibration generated by the moving media through the conduit is usually very small in amplitude and, consequently, its measurement requires that the conduit be virtually free of other vibrations which interfere with the primary flexural vibration generated by the electromagnetic vibrator and the secondary flexural vibration generated by the reaction of the moving media to the primary flexural vibration. In present day practice of the so called "convective inertia force" or "Coriolis force" mass flowmeters, a pair of parallel conduits of identical construction providing two parallel flow passages are laterally vibrated relative to one another by an electromagnetic vibrator exerting a vibratory force to the midsection thereof in an action-reaction relationship between the two conduits, which arrangement minimizes the leak of the momentum of the flexural vibration to the supporting structure, which leak of the momentum produces vibration noises interfering with the measurement of the secondary flexural vibration of the conduit proportional to the mass flow rate through the conduits. The present day practice employing the two parallel conduits has the following disadvantages: Firstly, the two parallel conduits divide the mass flow under measurement into two equal halves and weaken the intensity of the secondary flexural vibration of each conduit that is directly proportional to the mass flow rate through each conduit, as the mass flow rate through each of the two conduits is reduced to one half of the total mass flow under measurement. As a consequence, a mass flowmeter employing the two parallel conduits bifurcating the flow greatly reduces its capability to measure the mass flow rates at low flow velocities. Secondly, the employment of the two parallel conduits increases the cost of manufacturing and makes the flowmeter expensive and bulky.